Evolution Explained
The most fundamental concept is that living things change over time. These changes can aid the organism in its survival, reproduce, or become more adaptable to its environment.
Scientists have utilized genetics, a science that is new, to explain how evolution works. They have also used the science of physics to determine how much energy is needed for these changes.
Natural Selection
For evolution to take place organisms must be able to reproduce and pass their genetic characteristics on to future generations. This is a process known as natural selection, often described as "survival of the most fittest." However the term "fittest" can be misleading since it implies that only the strongest or fastest organisms can survive and reproduce. In fact, the best species that are well-adapted can best cope with the environment in which they live. Moreover, environmental conditions can change rapidly and if a group is no longer well adapted it will not be able to survive, causing them to shrink or even become extinct.
Natural selection is the most fundamental element in the process of evolution. It occurs when beneficial traits are more prevalent as time passes in a population which leads to the development of new species. This process is driven primarily by heritable genetic variations of organisms, which are a result of mutation and sexual reproduction.
Any force in the environment that favors or defavors particular characteristics could act as a selective agent. These forces can be biological, such as predators or physical, like temperature. Over time, populations that are exposed to various selective agents could change in a way that they are no longer able to breed together and are regarded as distinct species.
While the concept of natural selection is simple, it is not always easy to understand. Even among educators and scientists, there are many misconceptions about the process. Surveys have shown that students' understanding levels of evolution are only associated with their level of acceptance of the theory (see references).
For example, Brandon's focused definition of selection is limited to differential reproduction, and does not include inheritance or replication. But a number of authors, including Havstad (2011), have suggested that a broad notion of selection that captures the entire Darwinian process is adequate to explain both speciation and adaptation.
In addition there are a lot of instances in which a trait increases its proportion in a population, but does not alter the rate at which individuals with the trait reproduce. These cases may not be considered natural selection in the focused sense of the term but may still fit Lewontin's conditions for such a mechanism to function, for instance the case where parents with a specific trait produce more offspring than parents who do not have it.
Genetic Variation
Genetic variation is the difference in the sequences of genes of the members of a particular species. It is the variation that enables natural selection, which is one of the primary forces that drive evolution. Variation can be caused by mutations or through the normal process through which DNA is rearranged in cell division (genetic Recombination). Different gene variants may result in different traits, such as eye colour fur type, colour of eyes or the ability to adapt to changing environmental conditions. If a trait has an advantage, it is more likely to be passed on to future generations. This is referred to as a selective advantage.
A particular type of heritable variation is phenotypic, which allows individuals to change their appearance and behavior in response to the environment or stress. These changes can help them to survive in a different habitat or seize an opportunity. For example they might grow longer fur to protect themselves from the cold or change color to blend in with a specific surface. These phenotypic changes do not alter the genotype, and therefore cannot be considered to be a factor in evolution.
Heritable variation enables adapting to changing environments. Natural selection can be triggered by heritable variations, since it increases the likelihood that people with traits that favor an environment will be replaced by those who aren't. In some cases however the rate of variation transmission to the next generation may not be enough for natural evolution to keep pace with.
Many harmful traits such as genetic diseases persist in populations despite their negative consequences. This is due to a phenomenon referred to as diminished penetrance. It means that some people who have the disease-associated variant of the gene do not exhibit symptoms or symptoms of the condition. Other causes include gene by environment interactions and non-genetic factors such as lifestyle or diet as well as exposure to chemicals.
To better understand why negative traits aren't eliminated by natural selection, we need to understand how genetic variation affects evolution. Recent studies have revealed that genome-wide association studies that focus on common variants do not provide the complete picture of susceptibility to disease and that rare variants explain a significant portion of heritability. Further studies using sequencing are required to identify rare variants in worldwide populations and determine their impact on health, as well as the impact of interactions between genes and environments.
Environmental Changes
The environment can influence species through changing their environment. The famous story of peppered moths demonstrates this principle--the white-bodied moths, abundant in urban areas where coal smoke blackened tree bark and made them easily snatched by predators while their darker-bodied counterparts prospered under these new conditions. The opposite is also true that environmental change can alter species' abilities to adapt to changes they face.
Human activities are causing environmental changes at a global scale and the impacts of these changes are irreversible. These changes are affecting global ecosystem function and biodiversity. In addition they pose serious health risks to the human population particularly in low-income countries as a result of polluted air, water soil, and food.
For instance, the increased usage of coal by developing countries, such as India contributes to climate change, and also increases the amount of pollution of the air, which could affect the human lifespan. Additionally, human beings are consuming the planet's scarce resources at a rapid rate. This increases the chances that many people will be suffering from nutritional deficiency as well as lack of access to clean drinking water.
The impact of human-driven changes in the environment on evolutionary outcomes is a complex. Microevolutionary changes will likely alter the landscape of fitness for an organism. These changes can also alter the relationship between a particular characteristic and its environment. For instance, a study by Nomoto and co., involving transplant experiments along an altitude gradient showed that changes in environmental cues (such as climate) and competition can alter the phenotype of a plant and shift its directional selection away from its previous optimal match.
It is therefore essential to know the way these changes affect contemporary microevolutionary responses, and how this information can be used to predict the future of natural populations during the Anthropocene era. This is crucial, as the changes in the environment triggered by humans will have a direct impact on conservation efforts, as well as our health and existence. Therefore, it is essential to continue the research on the interaction of human-driven environmental changes and evolutionary processes on a worldwide scale.
The Big Bang
There are many theories about the creation and expansion of the Universe. None of is as well-known as the Big Bang theory. It has become a staple for science classes. The theory provides a wide variety of observed phenomena, including the numerous light elements, cosmic microwave background radiation as well as the vast-scale structure of the Universe.
At its simplest, the Big Bang Theory describes how the universe began 13.8 billion years ago as an unimaginably hot and dense cauldron of energy that has been expanding ever since. The expansion has led to all that is now in existence including the Earth and its inhabitants.
This theory is backed by a myriad of evidence. This includes the fact that we see the universe as flat, the kinetic and thermal energy of its particles, the temperature variations of the cosmic microwave background radiation as well as the densities and abundances of lighter and heavy elements in the Universe. The Big Bang theory is also suitable for the data collected by particle accelerators, astronomical telescopes and high-energy states.
In the beginning of the 20th century, the Big Bang was a minority opinion among physicists. Fred Hoyle publicly criticized it in 1949. After World War II, observations began to emerge that tilted scales in the direction of the Big Bang. Arno Pennzias, Robert Wilson, and others discovered the cosmic background radiation in 1964. talks about it is the result of a time-dependent expansion of the Universe. The discovery of this ionized radiation, which has a spectrum consistent with a blackbody around 2.725 K, was a major turning point in the Big Bang theory and tipped the balance in its favor over the competing Steady State model.
The Big Bang is a integral part of the cult television show, "The Big Bang Theory." In the program, Sheldon and Leonard make use of this theory to explain various phenomenons and observations, such as their research on how peanut butter and jelly are squished together.